Process of abrading



Oct. 30, 1934.

W. M GREGOR PROCESS OF- ABRADING Filed Nov. 2. 1931 INVENTOR wLuAM AGGREGOR 'ATTORNEY I ass on. so, 1934" PATENT OIFFICE PROCESS OF ABRADING r, Falls, N. Y., alsignor William MaeGrego to The Carbornndum Company, Niagara Falls,

N. Y., a corporation of Pennsylvania Application November 2, 1.81, Serial No.'51'2,603

' 4 Claims. (Cl. 51-278) This invention relates to an improved process sued to an approximately flat surface, making it of polishing, and more particularly to a process of removing scale and'of polishing by means of abrasive coated fabrics.

Heretofore, in the polishing of uneven and slightly wavy surfaces to the desired configuration by well-known grinding processes, appreciable amounts of stock have been removed. This is due to'the fact that the rough surfaces to be polished have miniature peaks and valleys and the apparatus bears much harder on the peaks than on the valleys, and the stock contained inthe peaks has to be removed.

My invention provides a process whereby scale, which may be either rolled or so-called pickling scale, is removed from the surface of any coated material. such as hot or cold rolled stock, either pickled or as rolled, as, for example, stretcher level steel,- without the removal of stock: furthermore, my invention provides a polishing or finishing operation upon the ductile and malleable material simultaneously with the removal of the scale therefrom.

As an improvement over the prior art, my process breaks the scale on the surface of the sheet by means of a flexible hammer which is made up from a flap of fabric which is coated with abrasive grains, small pieces of steel, or the like. A series of these flaps extend outward from a rotating drum and come sharply in contact, one at a time, with the scale upon the surface of the sheet and subject it to the hammering or breaking action of each abrasive grain or particle, each particle in itself acting as a minute hammer. Such hammering action breaks the scale into very small pieces, thus loosening it so that it may be easily and readily brushed from the'surface of the 7 sheet by a sweeping operation. The sweeping away of the loose particles from the surface of the sheet, accompanied by a polishing action, is ac-& complished by the dragging of the flaps over the fabric immediately after the breaking of the scale.

For purposes of illustrating my process, I

5 propose to describe its use in connection with stretcher level steel, but it is to be understood that my invention is not limited thereto and may be applied to such materials as have adherent scale, forged or rolled steel being a good example.

Stretcher levelsteel is the name applied to sheet steel which has been stretched by attaching clamps firmly on two opposite edges of a sheet of steel and applying tension by suitable power driven connections, whereby the sheet is straighb suitable for the manufacture of such articles as metal furniture and other special work. The term may be applied to sheets of any type of steel, or more specifically, to stainless sheets or 59 black sheets. Prior to the stretching operation, the sheets are rolled, this operation leaving a film of scale on the sheets, and it is this scale which must be removed. It should be understood that these sheets do not have absolutely plane surfaces, and that it is therefore impractical to grind off the scale with a rigidly bonded abrasive wheel.

This thin film of scale on the surface of the sheets is of a brittle nature, and since the surface of the sheets beneath the scale is ductile and malleable, the hammering action upon the scale and surface of the sheets, as performed by the abrasive grains coated upon the fabric flaps, in no way injures the steel immediately therebeneath; moreover; the brittleness of the scale insures its breaking without undue force or strain which might tend to slightly injure the stretcher level steel surface.

The grade of abrasive grain used upon these flaps for this breaking action is dependent upon the thickness of the scale to be removed. In order to easily remove a comparatively thick layer of scale, coarse grains of abrasive are necessary inasmuch as a heavy blow is needed to loosen the 85. scale surface. On the other hand, for a thin scale, a very fine .grit is necessary since coarse grains dig'into the steel surface and thereby remove some stock.

In the drawing illustrating my invention:

1 is a general view (somewhat diagrammatic in character) of the apparatus for rotating the drum;

'Fig. 2 is a partially sectional view showing a portion of a rotary member carrying a plurality of abrasive coated flaps and showing (looking in A the direction of the axis of rotation) a leather backing for partial support of the abrasive flaps. Fig. 3 is a diagrammatic microscopic view of a portion of the polished article, showing a typical form of scratched surface.

In carrying out my invention, reference being made to the drawing, the abrasive coated flaps .3 are secured to a drum 4 and extend through slots thereof. They are caused to move toward a radial position due to centrifugal force when the drum 4 is rotated by means of an electric motor '1, or any other suitable means, through speed reducing means 8. This rotating apparatus is placed in proximity to the surface of a sheet 2 wliichiis of any ductile material, having a top surface of brittle scale,and which is' moved in the same direction as the rotating drum 4, as indicated by arrows-in Fig. 1. It is to of the sheet 2, the abrasive coated flaps 3 sharply come in contact with the sheet- 2, causing the abrasive grains coated on these flaps to set up an action, simulating that of hammering, which breaks the brittle scale and other non-metallic means of any suitable kind are used to keep the impurities into particles. As the flaps 3 are moved forwardly and upwardly by the rotation of the drum 4, they draw or rub over the surface of the sheet 2, thereby brushing away the loose particles of scale, as well as loosening additional scale and impurities, and at the same time polishing the surface of the sheet 2. V

By provision of the flaps 3 and the grains coated thereon, any desired length of cut may be obtained, which is not the case with other processes, such as the belt sander and set-up wheel methods. With the belt sander method, the grains, because of equalized pressure over the entire surface, make only long cuts, together with the removal of appreciable amounts of stock. The set-up wheel process-necessitates the grains being positively, driven against the surface of the stretcher level steel, and this results in a grinding action and not the sought-for polishing action; however, since the amount of the flap 3 striking upon thestretcher level steel surface governs the length of cut, means are provided in my invention whereby the apparatus may be moved into close proximity to the stretcher level steel, or to a distance remote therefrom. A long out upon the surface of the stretcher level steel, which insures a high polish, is thus accomplished by arranging the apparatus in close proximity to the stretcher level steel so that the greater part of the flap will come in contact therewith and provide for a substantial drag across the surface. To secure a short out, which makes the surface particularly adaptable for the adherence thereto to other plane surfaces, the apparatus is placed a substantial distance from the stretcher level steel in order that only a very small portion of the rotating flap touches the scale upon the surface and thus doesnot dragacross the surface to prolong the cut. Cuts of varying lengths" are procured by the same process, the length of the cut secured being dependent on the distance between the rotating apparatus and the stretcher level steel surface.

The polish derived by this process is made up of numerous'short minute cuts which succeed and parallel one another in haphazard fashion, each individual out being somewhat tapering toward the end. More specifically, each cut is a trough of approximately V section and of diminishing depth toward the end' of the cut, as

shown in Fig. 3. This form of cut is produced,

, for example, by an abrasive grain, which strikes the surface tobe polished, producing a depression therein and the subsequent dragging of the grain .along' the surface with the result that the depth ofv the groove formed gradually diminishes in depth during the drag.

Should it bedesired to increase the effectiveness of the breaking and polishing action in the hollows of any rough surface, it isproposed to slit the ends of the flaps 3; moreover, the abrasive flaps may be so mounted in the rotating drum that upon the wearing down of" the abrasive grains upon the flaps, portions of these flaps which are worn may be severed therefrom, anda supply of fresh portions of abrasive fabric for the flaps 3 may be secured from the supply roll 5. This may be either by means of a central roll arranged to supply all the rolls, or by an individual supply roll for each flap. Locking aabric in the proper position with relation to the rum.

Various modifications of my inventionmay be made as for instance in Fig. 2 where the flap 3 is in'part supported by a mass 12 of leather or like flexible material, the mass being sufficient to move the flap 3 radially outward under the influence of centrifugal force acting mainly on the mass 12. Again,such increasing of the weight of the flap to make the grains hear more heavily on the surface of the steel may also be accomplished by increasing the thickness of the backing of the flap.

It will be apparent that my novel process provides a combination of breaking action and drawing action which is well adapted to scour the rough work surface with a simultaneous polishirtig kaction, without any undesired removal of s cc I do not wish to limit myself to the abrasive coated fabric of the example, as it is to be understood that such things as flexibly bonded abrasive sheets may be used equally as well; nor is it my desire in the use of fabric to limit myself strictly thereto as it is intended that such word will cover abrasive coated paper, cloth, or sheet materials of various kinds. My process may also be applied either with or without a cooling or coated metal sheet with an abrasive coated flap,

whereby the scale is detached from the metal. -2. In the manufacture of sheet metal, the method which comprises hammering an oxide scale coated metal sheet with an abrasive coated flap, and then drawing said abrasive coated flap over and in contact with the metal sheet, whereby the metal sheet is freed of scale and polished.

3. A method of removing scale from sheet metal which comprises hammering the metal sheet having scale thereon with an abrasive coated flap.

4. A method of removing scale from sheet metal which comprises hammering the metal sheet having scale thereon with an abrasive. coated flap and then drawing the said abrasive coated flap over and in contact with the sheet metal.

WILLIAM MACGREGOR.

lubricating agent by choosing abrasive material 

